Prefer `th->ec` for stack base/size. (#13101)

2 files changed, 27 insertions, 0 deletions

diff --git a/ext/-test-/stack/extconf.rb b/ext/-test-/stack/extconf.rb
new file mode 100644
index 0000000000..d786b15db9
--- /dev/null
+++ b/ext/-test-/stack/extconf.rb
@@ -0,0 +1,3 @@
+# frozen_string_literal: false
+require_relative "../auto_ext.rb"
+auto_ext(inc: true)
diff --git a/ext/-test-/stack/stack.c b/ext/-test-/stack/stack.c
new file mode 100644
index 0000000000..d69ca4da84
--- /dev/null
+++ b/ext/-test-/stack/stack.c
@@ -0,0 +1,24 @@
+#include "ruby.h"
+#include "internal/string.h"
+
+static VALUE
+stack_alloca_overflow(VALUE self)
+{
+    size_t i = 0;
+
+    while (1) {
+        // Allocate and touch memory to force actual stack usage:
+        volatile char *stack = alloca(1024);
+        stack[0] = (char)i;
+        stack[1023] = (char)i;
+        i++;
+    }
+
+    return Qnil;
+}
+
+void
+Init_stack(VALUE klass)
+{
+    rb_define_singleton_method(rb_cThread, "alloca_overflow", stack_alloca_overflow, 0);
+}